The Oklahoma City Thunder's hierarchy expressed their disappointment at Kevin Durant's decision to leave for the Golden State Warriors, but thanked him for his contributions to the franchise.

Durant put an end to the speculation on Monday by confirming he will join the Warriors, who the Thunder lost to in the Western Conference Finals this past season having led the seven-game series 3-1.

A four-time NBA scoring champion, Durant will now link-up with two-time MVP Stephen Curry as well as All-Stars Klay Thompson and Draymond Green as the Warriors attempt to avenge their Finals loss to the Cleveland Cavaliers.

He is expected to sign a two-year $54.3million with the Warriors, while Russell Westbrook will now serve as the primary star for the Thunder.

In statements, Thunder chairman Clayton Bennett and general manager Sam Presti each thanked Durant for his years in Oklahoma City, offering their appreciation for his play on the court, and how he represented the team and the region. 

Bennett said: "Kevin's contributions to our organisation during his nine years were profound, on and off the court. He helped the Thunder grow and succeed in immeasurable ways and impacted the community just the same.

"We thank him for his leadership, his play, and how he represented Oklahoma City and the entire state of Oklahoma."

Presti added: "Kevin made an indelible mark on the Thunder organisation and the state of Oklahoma as a founding father of this franchise. We can't adequately articulate what he meant to the foundation of this franchise and our success.

"While clearly disappointing that he has chosen to move on, the core values that he helped establish only lead to us thanking him for the many tangible and intangible ways that he helped our program."

Durant played nine seasons for the franchise and eight in Oklahoma City following the relocation of the Seattle SuperSonics. He played 641 games for the franchise, scoring 17,566 points (27.4 per game).